Molecular simulation and ablation property on the laser-induced metal surface

Abstract

As a kind of typical material for mechanical structure, stainless steel is often adopted in the high-power laser facility. Iron elements in stainless steel may play an important role in resisting the effect of laser ablation. Laser ablation of stainless steel or aluminium alloy can also cause metal particle contamination in high-power laser facility. The ablation processes on iron surface under laser irradiation are investigated with molecular dynamics (MD) simulation combined with two-temperature model. The trajectories of atoms in each region of single crystal iron under laser irradiation are analyzed in terms of the interaction between laser and iron. The simulation results show that atoms absorbing different energy show the macroscopic characteristics of different phases of single crystal iron. Studies have also shown that single atom and clusters of atoms may have a backlash effect on the material and cause stress waves. The propagation of stress waves is also analyzed. It is shown that the velocity of the stress wave is about 6.094 km/s. Ablation threshold of single crystal iron is determined by the movement of surface atoms under different laser energy densities and the simulation results show that ablation threshold of single crystal iron under femtosecond laser is 0.18 J/cm2. Meanwhile, it is also found that the instantaneous loading of laser energy has a greater effect on material ablation. This study can underpin for investigating the damage and contamination of precision mechanical component with stainless steel under the effects of laser irradiation.